FluidSim/Scenarios/TestScenario.cs

using System;
using SFML.Graphics;
using SFML.System;
using FluidSim.Components;
using FluidSim.Core;
using FluidSim.Utils;

namespace FluidSim.Tests
{
    public class TestScenario : Scenario
    {
        private Solver solver;
        private Volume0D volume;
        private Pipe1D pipe;
        private OrificeLink orifice;       // volume → pipe left
        private OpenEndLink openEnd;       // pipe right → atmosphere
        private SoundProcessor soundProcessor;
        private int stepCount;

        // Pressure reset scheduling
        private double simTime;
        private double dt;
        private double resetInterval = 0.2;          // seconds between resets
        private double nextResetTime;
        private double targetPressure = 10 * Units.atm;
        private double rampDuration = 0.002;          // 2 ms ramp
        private double rampStartTime;
        private double rampStartPressure;             // pressure when ramp started
        private bool ramping;

        public override void Initialize(int sampleRate)
        {
            dt = 1.0 / sampleRate;

            soundProcessor = new SoundProcessor(sampleRate, 1);
            soundProcessor.Gain = 2.0f;   // lower gain to avoid clipping

            solver = new Solver();
            solver.SetTimeStep(dt);
            solver.CflTarget = 0.4;

            volume = new Volume0D(1e-3, targetPressure, 300.0);
            solver.AddComponent(volume);

            pipe = new Pipe1D(1.0, 1e-4, 200);
            pipe.EnergyRelaxationRate = 10;
            solver.AddComponent(pipe);

            var volPort = volume.CreatePort();
            double orificeArea = 1e-5;
            orifice = new OrificeLink(volPort, pipe, isPipeLeftEnd: true,
                                      areaProvider: () => orificeArea)
            {
                DischargeCoefficient = 0.62,
                UseInertance = true,
                EffectiveLength = 0.001
            };
            solver.AddOrificeLink(orifice);

            openEnd = new OpenEndLink(pipe, isLeftEnd: false)
            {
                AmbientPressure = 101325.0,
                Gamma = 1.4
            };
            solver.AddOpenEndLink(openEnd);

            stepCount = 0;
            simTime = 0.0;
            nextResetTime = resetInterval;
            ramping = false;

            Console.WriteLine("Pressure reset test with smooth ramp");
            Console.WriteLine($"Volume 1L, reset to {targetPressure} Pa every {resetInterval*1000} ms, ramp {rampDuration*1000} ms");
        }

        public override float Process()
        {
            solver.Step();
            stepCount++;
            simTime += dt;

            // ---- Smooth pressure ramp ----
            if (ramping)
            {
                double elapsed = simTime - rampStartTime;
                if (elapsed >= rampDuration)
                {
                    // Ramp finished, set exactly to target
                    volume.SetPressure(targetPressure);
                    ramping = false;
                }
                else
                {
                    double frac = elapsed / rampDuration;
                    double currentTarget = rampStartPressure + (targetPressure - rampStartPressure) * frac;
                    volume.SetPressure(currentTarget);
                }
            }

            // ---- Trigger a new reset ----
            if (!ramping && simTime >= nextResetTime)
            {
                rampStartPressure = volume.Pressure;   // current pressure before reset
                rampStartTime = simTime;
                ramping = true;
                nextResetTime += resetInterval;
            }

            // Log every 500 steps
            if (stepCount % 500 == 0)
            {
                double volP = volume.Pressure;
                double pipeL = pipe.GetCellPressure(0);
                double pipeR = pipe.GetCellPressure(pipe.CellCount - 1);
                double mdotOrif = orifice.LastMassFlowRate;
                double mdotOpen = openEnd.LastMassFlowRate;

                Console.WriteLine($"Step {stepCount}: " +
                    $"VolP={volP:F1} Pa, PipeL={pipeL:F1}, PipeR={pipeR:F1}, " +
                    $"mdot_orif={mdotOrif:E4} kg/s, mdot_open={mdotOpen:E4} kg/s");
            }

            if (double.IsNaN(pipe.GetCellPressure(0)))
            {
                Console.WriteLine("NaN detected – stopping.");
                return 0f;
            }

            return soundProcessor.Process(openEnd);
        }

        public override void Draw(RenderWindow target)
        {
            float winWidth = target.GetView().Size.X;
            float winHeight = target.GetView().Size.Y;
            float pipeCenterY = winHeight / 2f;
            float margin = 60f;
            float pipeStartX = margin;
            float pipeEndX = winWidth - margin;
            DrawPipe(target, pipe, pipeCenterY, pipeStartX, pipeEndX);
        }
    }
}